Guided free film distillation apparatus



y 11, 1950 v s. w. FERRIS ETAL 2,514,943

eumsn FREE mu DIS-TILLATION APPARATUS Original Filed Jan. 29, 1945 2: Sheets-Sheet 2 war/unre- Figur 3 Inversion zqllesf Se mour M Fbrfz's E ward R. Lamdon G" Doug la: M. Smith W la fill! 5%(4/ Attorney Patented .luly 11, 1950 Guman mt FILM ms'rmmrrou APPARATUS "Seymour W. Ferris, Mount Holly, N. 1., and Edward R. Lamson, Hatboro, and Douglas M. Smith, Nor-wood, Pa., assignors to The Atlantic Refining Company, Philadelphia, Pa., a corporation of Pennsylvania Original application January 29, 1945. Serial No. 575,106. Divided and this application March 23, 1946, Serial No. 656,745

Claims. (Cl. 202-236) l The present invention relates to a guided free film distillation apparatus, and relates more particularly to an apparatus for short path distillation of organic substances under reduced pressure.

This application is a division of our copending application Serial Number 575,106, filed January 29, 1945, which issued as United States Patent 2,447,746 entitled "Guided Free Film Distillation Method."

It has been proposed heretofore to carry out short path distillation under low pressure by providing a heated vaporizing surface and a condensing surface adjacent thereto, and supplying to the vaporizing surface, the material to be distilled. Since the vaporizing surface was invariably at a higher temperature than the material charged to it for vaporization, partial decomposition of the material usually resulted, with the attendant deposition of carbonaceous material upon the vaporizing surface, and this despitethe very low pressures usually employed.

Ithas also been proposed heretofore to effect short path distillation under low pressure by jetting or spraying the material to be distilled between 9, source of radiant heat and a condensing surface, such material forming an unconfined spray or film capable of absorbing radiant heat in an amount sufficient to vaporize at least a portion of said spray or film. Since the material jetted or sprayed between the heat source and the condensing surface was unconfined, difllculty was encountered in controlling the spray or film and in preventing the unvaporized portions thereof from falling either upon the heat source or upon the condensing surface, and thereby decomposing upon the heat source or contaminating the distillate upon the condensing surface.

The above mentioned and other difficulties have been overcome in accordance with the present invention by supplying the heat of vaporization to the material to be distilled prior to forming same into a vaporizing film, thereby elimihating the use of a superheated vaporizing surface, and by guiding the vaporizing film of distillable material during its passage adjacent the condensing surface, thus avoiding contamination of the distillate with unvaporized material.

The apparatus of the present invention is adapted for use in the distillation of a wide variety of materials, and particularly in the evaporative or short path distillation of petroleum distillates, lubricating oils, residuums, petrolatum, wax, petroleum acids, and oils containing soaps such as the alkali and alkaline earth metal soaps of naphthenlc and sulfonic acids. Examples of other materials to which the present invention may be applied with advantage are animal and vegetable oils, fats, waxes, and concentrates thereof, and organic mixtures containing therapeutically active materials. The present invention is also of advantage in separating and purifying hormones, vitamins, enzymes, and the like from materials containing them, such as fish oils, corn oil, cottonseed oil, wheat germ oil, fatty vegetable extracts, etc.

In accordance with this invention, the organic material to be distilled is brought to a vaporizing temperature and formed into a continuously flowing film which is guided through a distilling vessel in close proximity to and out of contact with a condensing surface, the pressure within the vessel preferably being subatmospheric. In its passage through the vessel, components of the film are vaporized and the resulting vapors are condensed and separately withdrawn from the vessel. Undistilled residual material is likewise separately withdrawn, and all or a portion thereof may be recycled for further distillation. The condensing surface employed may be a solid surface suitably cooled, or may comprise one or a plurality of guided films of condensing liquid of the same or different composition as the vapors to be condensed. When distillation is eifected at very low pressures, the organic material to be distilled may be relieved of dissolved or occluded gas prior to introduction into the distilling vessel. While the present invention is particularly adapted for the distillation of materials at reduced pressure, such invention may also be applied in distillation at atmospheric or superatmospheric pressure.

The present invention may be further understood with reference to the accompanying drawing, in which Figures 1, 2, and 3 show diagrammatically apparatus suitable for carrying out the distillation process.

Referring to Figure 1, a vertical cylindrical chamber I enclosed in jacket 2 is provided with a partition 3 covering the cross-section of the chamber. The partition 3 is pierced with a plurality of apertures 4 extending in a line across the diameter of the partition. Disposed vertically within the chamber I are two guide rods 5 spaced horizontally from one another, one rod at each end of the row of apertures 4. On the side wall of chamber I are provided a plurality of annular troughs 6 spaced vertically from one another and extending completely around the chamber. The troughs are provided on one side with valve-controlled drawofl pipes I for withdrawing individual condensate fractions, and on the opposite side with valve-controlled drawofl pipes 8, each of which is connected to valve-controlled manifold for withdrawing all of the condensate fractions in one stream. At

the upper section of chamber I below partition 8- is provided a relatively large diameter pipe I connecting with means for reducing the pressure within the chamber. Such means (not shown) may comprise any suitable vacuum pump such as a mercury vapor pump, steam ejector pump, mechanical vacuum pump or a combinationof such pumps.

In operation, a distillable organic substance,

' for example, a viscous hydrocarbon oil is supplied from a source not shown through valve-controlled pipe I I and is pumped by pump I2 through tubular heater I3 wherein the temperature of the oil is raised, for example. to 350 F. Since it is desired to conduct the distillation at a low pressure and since the charge oil contains dissolved or occluded gas. such oil after leaving heater I3 is delivered by valve-controlled pipe I4 to the degassing chamber l5 connected by pipe I6 to a vacuum pump not shown. The degassing chamber is of conventional design and operation, and requires no further description. The heated oil, in passing through the degassing chamber I5 is subjected to reduced pressure and is relieved of its dissolved gas and any highly volatile hydrocarbons which it may have contained. The heated, degassed oil is then passed from chamber I5 by means of valve-controlled pipe I! into the upper or distributing section of distilling chamber I above the apertured partition 3. By regulating the rate of pumping a constant head of -oil may be maintained above the partition while the oil is fed through the apertures 4 in a plurality of fine streams which coalesce immediately below the partition and form a thin film or sheet across the space between the guide rods 5. The chamber I is maintained at the desired reduced pressure, for example, 10 to microns, by means of a vacuum pump connected through pipe ID. The heated oil continuously supplied to the rods 5 flows downwardly in a continuous film between rods 5, and during its passage a portion of the oil is vaporized by the contained heat and the vapors difiuse through the chamber, eventually coming into contact with the walls of the chamber and condensing thereupon. The chamber walls may be maintained at a suitable condensing temperature by circulating through the jacket 2 a cooling medium such as water or other agent.

- Since the most volatile constituents of the oil are the first to vaporize and diiIuse from the film, the most volatile condensate will be drawn oil from the uppermost trough 6, and the progressively less volatile condensates will be drawn oil at the successively lower troughs. In the apparatus illustrated, 3 difi'erent condensate fractions may be obtained by drawing from valve-controlled pipes I, or if desired, the condensates may be drawn from valve-controlled pipes 8 and combined into a single condensate in manifold 9, which condensate is then removed to storage not shown. The vaporizing oil film passing downwardly between rods 5 thus becomes progressively denuded of volatile constituents, and drains off the lower ends of the rods into the bottom of chamber I as undistilled residue. Such residual oil or bottoms is withdrawn from chamber I by means of valve-controlled ipe IO and may be sent to storage, or all or a portion of such residue may be returned by means of valve-controlled-pipe II to pipe II degassing chamber likewise may be dispensed with. While the distillation chamber I referred to in Figure 1 has been described as-being cylindrical. it is obvious that such chamber may be fabricated in other shapes, for example, chamber I may have an oval, square, or rectangular crosssection. Furthermore, in lieu of only two vertical guide rods 5, there may be employed a greater number of rods disposed in the same or diflerent plane and providing means for establishing a continuous vaporizing film of considerable width. If desired the vertical rods may be so disposed as to form an oval, circle, square, or rectangle within the distilling chamber, with condensing surfaces disposed inside or outside, or both insideand outside of, the oval, circle, square, or rectangle formed by the rods. Since the heat is supplied to the oil prior to the formation of the vaporizing film, the guide rods never acquire a temperature higher than that of the oil film which they guide. Therefore, decomposition of the oil and deposition of carbonaceous materials upon the rods is kept at a minimum.

Another modification of a distillation chamber and attendant equipment is illustrated in Figure 2 of the drawing.

Referring to Figure 2, a cylindrical chamber l' is provided in its upper portion with a partition 3 extending over the cross-section of the chamber. The partition is provided with a plurality of apertures 4' extending in a line across the diameter of the partition. Suspended vertically from the partition adjacent the end apertures thereof are two guide rods 5' spaced horizontally from one another, the lower ends of which terminate within a collecting funnel 2I. On either side of rods 5' and in a plane spaced horizontally from said rods, are a second pair of guide rods 22 extending upwardly from the bottom of chamber I and terminating beneath the partition 3'. Disposed above the ends of rods 22 and in the same plane is a pipe 23 provided with a plurality of apertures 24, the end of such pipe extending through the wall of chamber I. At the upper section of chamber l' below partition 3' is provided a relatively large diameter pipe Ill connecting with means for reducing the pressure within the chamber. Such means (not shown) comprises any suitable type of vacuum pump.

In operation, a distillable organic substance, for example, a crude residuum obtained from petroleum is supplied from a source not shown through valve-controlled pipe II and is pumped by pump I2 through tubular heater l3 wherein the temperature of the oil is raised, for example, to 400 F. Since it is desired to carry out the distillation at a very low pressure and since the charge 011 contains dissolved gas, such oil after leaving heater I3 is delivered by valve-controlled pipe I4 to the degassing chamber I 5' connected by pipe I6 to a vacuum pump not shown. The heated oil, in passing through the degassing chamber I5 is subjected to reduced pressure and is relieved of its content of dissolved gas. The

- wardly between rods 22.

chamber 1' above partition 3'.

heated, degassed oil is then passed from chamber 15' by means of valve-controlled pipe I? into the upper or distributing section of the distilling chamber l' above the apertured partition 3. By regulating the rate of pumping, a constant head of oil may be maintained above the partition while the oil is fed through the apertures 4 in a plurality of fine streams which coalesce immediately below the partition and form a thin film or sheet across the space between the guide rods 5'. The chamber l' is maintained at the desired low pressure, for example, 5 microns, by means of a vacuum pump connected through pipe Ill. The heated oil continuously supplied to the rods 5' flows downwardly in a continuous film between rods 5, and during its passage a portion of the oil is vaporized by the contained heat and the vapors diffuse through the chamber. To efiect condensation of these vapors, a liquid having a low vapor pressure is supplied to distributing pipe 23 whence it is delivered through apertures 24 to guide rods 22, whereby there is formed a condensing liquid film flowing down- The condensing liquid, being at a lower temperature than the oil vapors,

effects cooling and condensation of the vapors,

the resulting oil condensate traveling downwardly together with the condensing liquid film. Since the vaporizing film between rods 5' and the condensing film between rods 22 are traveling parallel'to one another and are in close proximity to but out of contact with one another, condensation of the vapors is efficiently carried out. The film of undistilled residue reaching the lower end of rods 5 drains therefrom into collecting funnel 2| and is withdrawn through pipe 24, and may be passed to storage through valve-controlled pipe 25. Or, all or a portion of the undistilled residue may be returned by means of valve-controlled pipe 26 to pipe II for recycling, with or without fresh charge oil, to the distributing section of The condensing liquid film and the condensate dissolved or entrained therein, upon reaching the lower end of guide rods 22, drains therefrom into the bottom of chamber I and is withdrawn by means of valve-controlled pipe 21 and may be passed to storage or to further treatment through valvecontrolled pipe 28. In the event that the condensing liquid consists of the oil condensate itself, I

a portion thereof may be passed from valve-controlled pipe 21. by means of pump 29 through cooler 30 and valve-controlled pipe 3| to the distributing pipe 23, the remainder being passed from the system through valve-controlled pipe 28. If, on the other hand, the condensing liquid comprises a low vapor pressure fluid other than the condensate, such fluid may be supplied from a source not shown by means of valve-controlled pipe 32. Should the distillation be carried out at atmospheric or higher pre'ssures, the condensing liquid need not have a low vapor pressure, i. e., water or other fluids may be used. While, in Figure 2, only one condensing film has been shown it is, of course, desirable to provide a second condensing film on the opposite side of the vaporizing film. This may readily be accomplished by providing a second set of guide rods similar to rods 22 to guide the second condensing film, the condensing liquid distributing apparatus being similar to that already shown.

A further modification of apparatus suitable for carrying out the process of the present invention is illustrated in Figure 3 of the drawing, in which the distillation chamber is shown as an end view rather than as a side view as in Figure 2.

' of apertures being horizontally spaced from one another. Disposed vertically at each end of each series-of apertures are guide rods 36, the lower ends of which terminate within alternate collecting channels 31 formed by partitions 38 extending transversely across the bottom of chamber 33. Also disposed vertically within chamber 33 between each of the sets of guide rods 36 and spaced horizontally therefrom, are a plurality of guide rods 39, one rod being placed at each end of each apertured distributing pipe 40, a plurality of which are connected to manifold 4|. The guide rods 39 terminate within alternate collectin channels 42. At the mid-section of the back wall of chamber 33 are provided a-plurality of relatively large diameter openings 43 connected to pipe 44, which in turn leads to a suitable means for evacuating chamber 33, such means comprising a vacuum pump not shown.

' The distilling chamber 33 comprises, in effect, a rectangular vessel containing alternate sets of guide rods 36 and 39 for guiding alternate vaporizing and condensing films, respectively, the material to be distilled being supplied above apertured partition 34, and the condensing liquid be-.

ing supplied through the apertured pipes 40. The condensing liquid and condensate is collected and withdrawn from channels 42, and the undistilled residue i collected andwithdrawn from channels 31, as will be described in detail hereinafter.

In operation, a distillable organic substance, for example, ahigh viscosity hydrocarbon lubricating oil stock, is supplied from a source not shown through valve-controlled pipe 45 and is pumped by pump 46 through a heating means such as tubular heater 41 wherein the temperature of the oil is raised, for example, to 330 F. The heated oil is then passed through valve-controlled pipe 48 to degassing chamber 49 connected to a vacuum pump (not shown) by means of pipe 50. Herein, the hot oil is subjectedtoreduced pres sure and the dissolved gases are removed. The degassed oil is passed from chamber 49 through valve-controlled manifold 5! into the upper section of distilling chamber 33 above the apertured partition 34. If the oil is already degassed or if the distillation was to be effected at atmospheric or higher pressure the degassing chamber may be dispensed with, and the oil delivered through valve-controlled pipe 56 to manifold 5|. By regulating the rate of pumping, a constant head of oil may be maintained above the partition 34 while the oil is fed through the plurality of series of apertures 35 to the guide rods 36, thereby forming a plurality of continuously flowing vertical films guided by rods 36. The chamber 33 is maintained at the desired reduced pressure, for example, 50 microns, by means of a vacuum pump connected to pipe 44. During the passage of the guided oil films downwardly through the chamber 33, a portion of the oil is vaporized by its contained heat, and the vapors diffuse from the films into the chamber. The films of undistilled residue or bottoms reaching the lower ends of rods 36 drain from the rods into channels 31 and are withdrawn through manifold 52. The bottoms 'may be sent to storage through valve-controlled The partition is provided with a plupipe 63, or all or any portion of such bottoms may be returned through valve 64 to pipe 45 for recycling, with or without fresh charge oil, to the distillation chamber for further distillation.

To effect condensation of the vapors difiused from the vaporizing films, a condensing liquid of low vapor pressure is'supplied through manifold 4| to the apertured distributing pipes 49, and is fed from the apertures onto the rods 39, thereby forming a, plurality of continuously flowing vertical condensing films guided by the rods 39. The condensing liquid, being at'a lower temperature than the oil vapors, effects cooling and condensation of the vapors, the resulting condensate traveling downwardly together with the condensing film. The condensing liquid films and the condensate dissolved or entrained therein, upon reaching the lower ends of guide rods 39 drains therefrom into the channels 42 and is withdrawn therefrom through manifold 55. Depending upon the nature of the condensing liquid, various techniques may be applied in the handling thereof as follows:

In the event that the condensing liquid consists of the oil condensate itself, such liquid may be drawn from manifold 55 and a portion thereof passed to storage through valve-controlled pipe 51, while the remainder is delivered by pump 58 and valve-controlled pipe 59 to cooler 60, wherein the liquid is cooled to a suitable temperature and then supplied through valve-controlled pipe 6| to manifold 4| for reuse as condensing fluid.

On the other hand, if the condensing fluid is relatively immiscible with the oil condensate, the immiscible mixture after passing through cooler 60 is introduced through valve-controlled pipe 62 into settling vessel or separator 63 wherein the immiscible mixture of oil condensate and condensing liquid is permitted to settle and stratify into layers, the condensing liquid forming the upper layer if the specific gravity'of such liquid is lower than that of the oil. The upper layer is continuously drawn ofi through valve-controlled pipe 64 and returned to manifold 4| for reuse as condensing liquid. The lower layer of oil condensate is drawn from the bottom of separator 63 by means of valve-controlled pipe 65 and passed to storage not shown. In the event that the oil condensate has a lower specific gravity than the condensing liquid, the connections will be reversed whereby the oil condensate is drawn from the top of the separator and the condensing liquid from the bottom of the separator for return to manifold 4|.

Finally, if the condensing liquid is miscible or partially miscible with the oil condensate and has a boiling point or boiling range different than thatof the oil condensate, the mixture or solution of oil condensate and condensing liquid is delivered by pump 58 through valve-controlled pipe 66 to fractionating or stripping column 61 provided with bubble trays 68, heating oil 69, and dephlegmating coil 10. Assuming that the condensing liquid has a lower boiling point or range than the oil condensate, the mixture in passing downwardly through the column is subjected to fractionation, the necessary heat being supplied primarily by the heating coil 69. The condensing fractionation operation may be drawn from the bottom of column 61, cooled, and passed to storage through valve-controlled pipe 16. On the other hand, if the condensing liquid is higher boiling than the oil condensate, the condensate" will be vaporized and taken overhead and the condensing liquid will be drawn as bottoms.

In the operation of the distilling apparatus at low pressures, for example, 250 microns or less, it is necessary to employ condensing liquids having a relatively low vapor pressure at the condensing temperature, otherwise a low pressure could not be maintained in the apparatus. However, if the temperature of the condensing liquid film is very low, the'actual boiling point of the condensing liquid is of little consequence, since its vapor pressure would necessarily be low. Suitable condensing liquids include the condensate, per se, whether it be hydrocarbon oil or other condensate produced by the distillation. Various other compounds may also be employed, such as glycerol, glycol, the polyglycerols and polyglycols, organic esters of the acids of phosphorus, phthalic acid esters of aliphatic and aromatic alcohols including ethyl hexyl phthalate, ethyl lactate, fatty oils, and the like. When the condensing liquid temperature is maintained at a low level, more volatile liquids may be utilized, including halogenated hydrocarbons, aliphatic alcohols, ethers, ketones, nitroparaflins, nitroaromatics, hydrocarbon distillates, gas oil, water, aqueous solutions of soluble salts, sugar solutions, etc.

The method of the present invention is applicable to the distillation of distillable organic substances at temperatures up to the decomposition temperature at the prevailing pressure. In general, evaporative distillation may be effected at temperatures up to 600 F., temperatures of the order of 250 F. to 400 F. being suitable for most hydrocarbon oils of substantial viscosity and boiling point, pressures being of the order of microns or less, and preferably 10 microns or less. It is, of course, obvious that the distillation proc- (255 may be carried out not only in a single continuous unit such as shown in Figures 1, 2, and 3, but also in a plurality of such units in series or parallel operation. In series operation the undistilled residue from the first unit may be subjected to further distillation in a second unit at the same temperature and at a lower pressure, or at a higher temperature at the same or lower pressure. The undistilled residue from the second unit may be charged to a third unit and the distillation continued, such process being repeated until further distillation becomes impractical.

While the present invention is particularly applicable to the evaporative distillation of organic compounds, for example, oils, fats, waxes, and resins, such invention may be likewise employed in the distillation of inorganic substances or mixtures, including sulfuric acid; phosphoric acid; sulfuric acid contaminated with hydrocarbons, hydrocarbon polymers, or esters; sulfuric or phosphoric acid sludge from the processing or refining of petroleum or other hydrocarbons; decomposable inorganic salt solutions, and the like.

The apparatus illustrated in Figures 1, 2, and 3 is, of course, capable of being modified in many ways in order to obtain the highest operating efficiency, depending upon the nature and properties of the material to be distilled. For example, depending upon the viscosity and the rate of charge of the material as well as the pressure tility of the material.

under'which the distillation is conducted, the

width of thevaporizing film may vary from several inches to several feet. At low pressure, wider fllmsmay be employed, since there is less disturbance of the film, i. e., weaving or billowing, than at atmospheric or higher pressures. Furthermore, the length of the vaporizing film may vary from a few feet to or 20 feet or more, depending upon the rate of charge and the vola- The strength of the vaporizing film may be increased by the addition of. surface tension reducing agents such as soaps. fatty acids, and esters which may remain in the vaporizing .film during distillation. Moreover, various means may be employed in distributing the material comprising the vaporizing film and the condensing film. For example, in lieu of a partition or pipe provided with a plurality of apertures as shown in Figures 1, 2, and 3, other means such as weires, dams, nozzles, or short tubes may be utilized. It, of course, will be apparent that the apertures 4 will be reasonably closely spaced and of relatively small diameter, depending upon the material to be distilled. In the example which follows, a series of inch diameter openings spaced on A; inch centers was employed.

The results obtained in the practice of the present invention are given in the following examples in which a viscous hydrocarbon oil, after degassing, was distilled in an apparatus similar to that shown in Figure 1 of the drawing, the entire oil condensate being taken as a single fraction. Such examples are illustrative only and are not to be construed as limiting the scope of the invention. The vaporizing film was 28 inches in length and 1% inches in width, giving a total vaporizing surface of 0.632 square foot. The properties of the charge oil and the resulting distillate, as well as the operating conditions are tabulated below.

Filtered Pennsylvania Residuum Charge Oil:

A. P. I. Gravity degrees 30.0 26. 9 SU Via/100 F--- "seconds" 592 2, 322 SU Vie/210 F do 61 148 Volume charged-. cubic centimeters 4, 140 4, 140 Distillation Temp., F 0-260 290-352 Distillation Pressure, microns Distillate:

A. P. I. Gravity degrees 30. 7 29.3 SU Vis./l00-F 116 235 SU Vie/210 F 41 48 Volume Distillate .cubie centimeters 243 340 Bottoms:

- A. P. I. Gravity degrees 28. 7 26.6 SU Via/100 F seconds 761 2, 386 SU Via/210 F--- do 61 151 Volume Bottoms ubic centimeters 3, 870 3, 540

The apparatus of the present invention presents several advantages over the apparatus heretofore known to those skilled in the art. More particularly, the preheating of the material to be distilled prior to forming same into a vaporizing film and thus utilizing the contained heat to effect distillation avoids the use of internal heaters or solid heated surfaces which are prone l0 vaporizing surface since vaporization takes place from both sides of the guided free film, whereas in films flowing over solid surfaces, vaporization may only take place from the surface not in contact with the solid.

We claim:

1.'Evaporative distillation apparatus comprising a chamber, a plurality of guide rods vertically disposed within said chamber and horizontally spaced from one another a distance sufiicient to support a free-flowing film of a distillable substance therebetween, distributing means having a series of apertures positioned above and extending between said guide rods for supplying thereto and forming therebetween a free-flowing film of a distillable substance, and means for separately collecting and withdrawing distillate and undistilled residue from said chamber.

2. Evaporative distillation apparatus comprising a chamber, a plurality of guide rods vertically disposed within said chamber and horizontally spaced from one another a distance suificient to support a free-flowing film of a distillable substance therebetween, distributing means having a series of apertures positioned above and extending between said guide rods for supplying thereto and forming therebetween a free-flowing film of a distillable substance, condensing means in close proximity to and out of contact with said guide rods, means for collecting and withdrawing condensed distillate from said condensing means, and means for separately collecting and withdrawin undistilled residue from said chamher.

3. Evaporative distillation apparatus comprising a chamber, a plurality of guide rods vertically disposed within said chamber and horizontally spaced from one another a distance suflicient to support a free-flowing film of a distillable substance therebetween, a partition means having a series of aperturespositioned above and extending between said guide rods for supplying thereto and forming therebetween a free-flowing film of a distillable substance, condensing means in close proximity to and out of contact with said guide rods, means for collecting and withdrawing condensed distillate from said condensing means, means for separately collecting and withdrawing undistilled residue from said chamber, and means for maintaining a subatmospheric pressure within said chamber.

4. Evaporative distillation apparatus comprising a chamber, a plurality of guide rods vertically disposed within said chamber and horizontally spaced from one another a distance sufficient to support a free-flowing film of a distillable substance therebetween, distributing means having a series of apertures positioned above and extending between said guide rods for supplying thereto and forming therebetween a free-flowing film of a distillable substance, condensing means in close proximity to and out of contact with said guide rods comprising a second plurality of vertically disposed guide rods horizontally spaced from one another a distance sufllcient to support a free-flowing film of a condensing liquid therebetween, and distributing means having a series of apertures positioned above and extending between said second plurality of rods for supplying thereto and forming therebetween a free-flowing film of a condensing liquid.

5. Evaporative distillation apparatus comprising a chamber, a plurality of guide rods vertically disposed within said chamber and horizontally spaced from one another a distance sum- 11 cient to support a tree-flowing film of a distillable substance therebetween, distributing means having a series of apertures positioned above and extending between said guide rods for supplying thereto and forming therebetween a free-flowing film of a distillable substance, condensing means in close proximity to and out of contact with said guide rods comprising a second plurality of vertically disposed guide rods horizontally spaced from one another a distance sufiicient to support a free-flowing film of a condensing liquid therebetween, distributing means having a series of apertures positioned above and extending between said second plurality oi rods for supplying thereto and forming therebetween a free-flowing film of a condensing liquid, means for collecting and withdrawing condensed dis- 12 tillate from said condensing means, and means for separately collecting and withdrawing undistilled residue from said chamber.

SEYMOUR W. FERR-IS. EDWARD R. LAMSON. DOUGLAS M, SMITH.

REFERENCES- CITED The following references are of record in the 0 file of this patent:

UNITED STATES PATENTS Number Name Date 1,007,967 Pampe Nov. 7, 1911 15 1,932,405 Harris Oct. 31, 1933 2,370,462 Heckler Feb. 27, 1945 

